Allegro MicroSystems Inc.'s complete three phase brushless DC
motor pre-driver has outputs for direct high current gate drive of an all
N-channel power MOSFET. The three phase bridge has a maximum supply voltage of
38 V. The A4938 includes Hall element inputs, a sequencer
for commutation control, fixed off time pulse width modulation (PWM) current
control and locked rotor protection. Output current is scalable with the choice
of external MOSFETS. ENABLE, DIRECTION and BRAKE inputs can be used to control
the motor, speed, position and torque. Output speed can be regulated using open
drain FG1 output that changes state at each Hall transition.
external MOSFETS can be PWM'd with the ENABLE input or with the internal PWM
current regulator. In both cases the A4938 synchronous rectification feature
will turn on the appropriate MOSFET(s) during current decay to reduce power
dissipation. The A4938 uses low cost Hall elements with noise filtering to
prevent false commutation signals. A 5V regulated supply output is provided to
power the three HALL elements. Internal circuit protection includes thermal
shutdown with hysteresis, under voltage lockout, over voltage protection with
two voltage settings, locked rotor and dead time protection. Special power up
sequencing is not required. Operating temperature range is -40 to 85C. The A4938EETTR-T is supplied in a 5 ×
5 mm 28-lead QFN package with exposed thermal pad.
Robots that walk have come a long way from simple barebones walking machines or pairs of legs without an upper body and head. Much of the research these days focuses on making more humanoid robots. But they are not all created equal.
The IEEE Computer Society has named the top 10 trends for 2014. You can expect the convergence of cloud computing and mobile devices, advances in health care data and devices, as well as privacy issues in social media to make the headlines. And 3D printing came out of nowhere to make a big splash.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.